Data storage systems are arrangements of hardware and software that include one or more storage processors coupled to arrays of non-volatile storage devices, such as magnetic disk drives, electronic flash drives, and/or optical drives, for example. The storage processors service storage requests, arriving from host machines (“hosts”), which specify files or other data elements to be written, read, created, or deleted, for example.
Data storage systems commonly employ replication technologies for protecting the data they store. Conventional replication technologies include those providing continuous replication and those providing snapshot shipping. Well-known continuous replication solutions include RecoverPoint and MirrorView systems, which are available from EMC Corporation of Hopkinton, Mass. RecoverPoint systems include a replication splitter and one or more local replication appliances provided both on a source data storage system (source) and on a destination data storage system (destination). As the source processes IO requests specifying data to be written to a particular LUN (Logical Unit Number), the replication splitter on the source intercepts the IO requests and sends them to a local replication appliance (or appliances). The local replication appliance communicates with a replication appliance at the destination, and the two appliances orchestrate storage of the data specified in the IO requests at the destination. In this manner, the destination is made to store a redundant copy of the data of the LUN stored at the source, and the redundant copy at the destination may provide a means for recovering the contents of the LUN in the event of a failure at the source. MirrorView systems perform similar functions to those described for RecoverPoint, but communicate directly between a source and a destination with no intervening replication appliances.
A well-known snapshot-shipping replication solution is the Celerra Replicator™ V2, also available from EMC Corporation of Hopkinton, Mass. Replicator V2 operates by taking snaps (i.e., point-in-time copies) of files and file systems at a source, identifying differences between current snaps and previous snaps, and sending the differences to a destination. The destination receives the differences and applies them to replicas maintained at the destination, to update the replicas with changes made at the source.